1. Field of the Invention
The present invention relates to a variable station platform with one or more platform slabs.
2. Description of the Related Art
In conventional construction, station platforms are described as a stationary structure. Such station platforms are produced on the precondition that they should remain unchanged for many generations. However, static structures of this kind no longer meet the requirements of modern rail traffic. On the one hand, they are inflexible with regard to requirements emanating from new technical developments. On the other hand, they do not provide the possibility of carrying out unavoidable corrections relating to dimensions and spacings on the structure at a later time in a straightforward and cost-effective manner. Under the modern requirements for comfort and safety, it is no longer acceptable to tolerate such deviations without correction. Moreover, the conventional station platforms are to be criticized from a current standpoint for the complex, time-consuming and cost-intensive construction which impedes operation.
To simplify the construction of station platforms, in the past there have been attempts to use prefabricated kits for station platforms. For instance, EP-357 161 thus describes a station platform which is made up essentially of three basic elements. These are firstly U-shaped concrete pedestals which are set at fixed intervals parallel to the course of the rails.
Two longitudinal beams are then placed on the vertical limbs of the U-shaped concrete pedestals from one pedestal to another, which longitudinal beams run parallel to the rail. Subsequently, the longitudinal beams are covered from above with rectangular platform slabs, and all the connections and joints are closed and bonded. A station platform system of this type may reduce the construction time of a station platform compared to the fixed construction, but the handling of the solid longitudinal beams and the many platform slabs is still relatively complex. Moreover, the platform slabs are not protected against bending or "sagging" toward the unsupported center between the two longitudinal beams. A particular disadvantage should furthermore be mentioned, that the station platform is not suitable for later reconstruction without difficulty due to the permanently applied connection of the construction elements and, in particular, does not permit any dimensional adaptation of the system at all.
A station platform kit is also described in DE-43 16 203, which contains concrete foundations cast in situ, transverse beams and platform slabs. Here the transverse beams are attached to the concrete foundations cast in situ and platform slabs are then laid from one transverse beam to another, the said platform slabs containing support beams molded on to their underside in a box shape. These platform slabs are fixedly connected to the transverse beams. This system has similar disadvantages to those described above.
In particular, no provision is made for dimensional adaptation and height-adjustability, and the fixed connection of the components to one another results in a structure which cannot easily be changed at a later date.
In the laid-open publication DE 42 05 192 A1, a station platform is described, in which so-called spacer elements are arranged so as to be fixed against displacement on concrete foundations cast in situ and founded with spacing along the rail. Longitudinal supports which are parallel to the rails and parallel to one another are then laid from one spacer element to another and finally support a concrete slab cast in situ as the station platform. All the construction elements are secured against lateral displacement by means of bolts or similar means which pass right through. The laid-open publication emphasizes as an advantage the fact that, if the station platform is reconstructed at a later date, its height can easily be changed by raising the concrete slab cast in situ and replacing the spacer elements for different spacer elements. The station platform is produced at the site of installation in order that it can be made in one piece and to achieve better adaptation to curved areas. However, this production on site also has several disadvantages. On the one hand namely, permanent formwork is used which is only fixed in grooves. The width of the station platform is therefore limited for purely structural reasons because of the high loads exerted by the concrete covering cast in situ on the permanent formwork. Furthermore, concrete cast in situ must be allowed to set for up to 28 days, which extends the required construction time. Additionally, influences of weathering and frost may impede the construction site.
Furthermore, the station platform represented in the laid-open publication is a complete station platform as a rigid slab. This slab can only be removed by cutting the concrete. The destruction of the reinforcement therefore makes its reusability extremely limited.
A station platform (for streetcars) which is adjustable in height is also described in the article "Versenkbare Verkehrsinseln" [Lowerable traffic islands] (Verkehrstechnik [Traffic technology], Volume 24, Dec. 20, 1935, page 666). Here the platform slab rests in the normal state on four wooden blocks. By removing the wooden blocks, it can be lowered into the ground, i.e. adapted to street level. In this case, the platform slab is vertically movable within a given shaft.
The height-adjustability of the traffic island or the platform system disclosed in the abovementioned publication and in DE 42 05 192 A1 can, however, result in problems in practice, since the desired spacing of the platform edge from the axis of the track may vary between customary platform heights (e.g. 38 cm above the upper edge of the rails (SOK)) and greater platform heights (e.g. 55 cm, 76 cm and 96 cm above the SOK). In these cases, the height-adjustment may result in an undesirably and unacceptably large distance of the platform from the axis of the track or from the entrance to the carriage.